Considering a quality machine, not one which you can find in a big box store, are there popular or preferred brand of vacuum cleaner to market and sell, and/or that customers prefer?
are few in number, and in order of number of skus from greatest to least: Hoover, Dirt Devil, with Electrolux, Eureka and Dyson tied for third, and the occasional Dyson.
Vac shops tend to have Miele, Tacony, Perfect, Panasonic, Lindhaus, and Sebo, and the BB lineup.